Stéphane your previous question makes me think of a better solution with requires only one mandatory class and which makes use of standard event notification (without PreferenceCollector). I've joined 4 packages : - PrefCore contains PreferenceValue which is now the only mandatory class. 2 packages for testing: - PrefProvider contains PrefProvider class which declares some preferences - PrefUser contains PrefChangeListener (try PrefChangeListener test). 1 package for UI: - PrefTool contains PreferenceCollector and PreferenceDefinition. They are optional. Code below do not makes use of PreferenceCollector anymore: PrefChangeListener>>initialize super initialize. gradientLook := PrefProvider gradientButtonLook value. "reading of the preference value" "Using of standard event notification engine" PrefProvider when: #gradientButtonLook send: #gradientButtonLookIsNow: to: self. PrefProvider when: #gradientButtonLook send: #gradientLook: to: self. Now, the preference system only need PreferenceValue. PreferenceCollector and PreferenceDefinition are optional and can be brought by a preference supporting tool (UI). Previous version implied a dependency from PrefChangeListener to PreferenceCollector which was bad. PrefChangeListener>>initialize super initialize. gradientLook := PrefProvider gradientButtonLook value. PreferenceCollector whenChanged: #gradientButtonLook inClass: PrefProvider notify: self using: #gradientButtonLookIsNow: . PreferenceCollector whenChanged: #gradientButtonLook inClass: PrefProvider notify: self using: #gradientLook: alain Stéphane Ducasse a écrit :
sounds cool. For me the most important aspect is that preferenceCollector (our current preference class should be a removable layer on top of the system that are declaring preference.
Is is correct that
PreferenceCollector whenChanged: #gradientButtonLook inClass: PrefProvider notify: self using: #gradientButtonLookIsNow: .
means that PrefProvider will receive the message gradientButtonLookIsNow:
no, but see the code below: ----------- PrefListener>>initialize super initialize. PreferenceCollector whenChanged: #gradientButtonLook inClass: PrefProvider notify: self using: #gradientButtonLookIsNow: . ----------- it means that a PrefListener instance will receive the #gradientButtonLookIsNow: message each time the preference #gradientButtonLook defined in class PrefProvider is changed. PrefListener and PrefProvider represent can be any class in the system. So, in order to read a preference value an object get it from the provider class by message sending, the provider is a class in a package which defines preferences (no need for PreferenceCollector to get the preference value).
This way we can push preference to the tools
yes
and thety do not have to query the information in the Collector at run-time
yes, Each package have its own preference set in it represented by a set of methods with pragma. When such a package is loaded, its preferences are automatically stored by PreferenceCollector. When a package is removed, its preferences are automatically removed from PreferenceCollector. PreferenceCollector is only here for supporting tools (cool UI ...) and for change notifications.
(hence we could remove Preference and have a more OO design).
I guess yes.
Sorry not to reply earlier (I was breaking yet another wall in our "kitchen")
bon courage :) alain
Stef
On Mar 1, 2009, at 10:05 AM, Alain Plantec wrote:
Hi all,
joined Zoo package is a attempt to translate in code what we discussed here before about preference refactoring.
The framework is made of 3 classes: PreferenceCollector, PreferenceDefinition and PreferenceValue. In Zoo there are also 2 classes for testing: PrefProvider and PrefChangeListener. PrefProvider class declares some preferences and PrefChangeListener is here to test preference change notification.
PrefChangeListener>>initialize super initialize. PreferenceCollector whenChanged: #gradientButtonLook inClass: PrefProvider notify: self using: #gradientButtonLookIsNow: . PreferenceCollector whenChanged: #gradientButtonLook inClass: PrefProvider notify: self using: #gradientLook:
PrefChangeListener class>>test "self test" PrefChangeListener new inspect. PrefProvider gradientButtonLook: PrefProvider gradientButtonLook value not. PrefProvider gradientButtonLook: PrefProvider gradientButtonLook value not. PrefProvider gradientButtonLook: PrefProvider gradientButtonLook value not.
From PreferenceCollector comment: -------------------------------------- A PreferenceCollector automatically collects all preferences. A preference is represented by a PreferenceDefinition. All PreferenceDefinition are stored in the preferences instance variable.
Instance Variables preferences: OrderedCollection of PreferenceDefinition
preferences - contains all PreferenceDefinition which are automatically built from pragma found in preference getters
ADDING A PREFERENCE PreferenceCollector makes use of the SystemChangeNotifier in order to automate the adding, the removing and the updating of preferences. See #PreferenceCollector>>event: to see how preferences update is implemented.
Editing a new method with a preference pragma or inserting a preference pragma in an existing method are the two ways for preference definition adding. The only way to remove a preference definition is to remove the corresponding method.
Example of a "blackAndWhite" preference. Methods below are defined by the preference provider APreferencePrivider class. Note that the value stored in BlackAndWhite class variable is an instance of PreferenceValue. In this example, the default value is directly given with the pragma: ------------- APreferencePrivider class>>blackAndWhite <preference: 'Use black and white' type: #Boolean set: #blackAndWhite: defaultValue: false description: 'Use black and white'> ^ BlackAndWhite ifNil: [BlackAndWhite := PreferenceValue value: false location: self selector: #blackAndWhite]
APreferencePrivider class>>blackAndWhite: aBoolean self blackAndWhite value: aBoolean -------------
If a default value can't be specified in the pragma, another way consists in using a selector which represents the message to send to the class in order to get the default value:
------------- APreferencePrivider class>>standardFont <preference: 'The default system font' type: #LogicalFont set: #standardFont: default: #defaultStandardFont description: 'The default system font'> ^ StandardFont ifNil: [StandardFont := PreferenceValue value: self defaultStandardFont location: self selector: #standardFont]
APreferencePrivider class>>standardFont: aFont self standardFont value: aFont APreferencePrivider class>>defaultStandardFont ^ LogicalFont familyName: 'Arial' fallbackFamilyNames: nil pointSize: 12 stretchValue: 5 weightValue: 400 slantValue: 0 -------------
LISTENING TO A PREFERENCE VALUE CHANGE Any object can register itself as a preference value change listener. See #PreferenceCollector class>>whenChanged: inClass:notify:using:.
Each time a preference value is changed, #preference: inClass:changedWith: is sent to the PreferenceCollector class.
Example of code a listener can implement in order to be notified each time a gradientButtonLook preference defined by a PrefProvider class is changed. In this example, the listener ask to be notified by a send of #gradientButtonLookIsNow: message. The argument given to gradientButtonLookIsNow: is the new preference value. ------------- .... PreferenceCollector whenChanged: #gradientButtonLook inClass: PrefProvider notify: self using: #gradientButtonLookIsNow:. .... -------------
What do you think ?
cheers Alain
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